Food resources are often patchily distributed through space and time and are classified as resource pulses when hyperabundant. Resource pulses can benefit growth, reproduction, and abundance of various consumers. Yet, it is relatively unknown how such resources are partitioned among competing consumers and how this is influenced by the magnitude of the pulse. Here, we examined how the magnitude of a pulsed resource influences resource partitioning among diverse sizes and species of consumers in a natural setting over small spatial and temporal scales. We focused on salmon egg subsidies to stream fish consumers. We experimentally added different quantities of pink salmon eggs to five meter long experimental stream sections. Egg additions spanned three orders of magnitude from 6 to 3575 eggs. Stream fish (egg consumers) were captured and gastric lavaged at each experimental section to determine how many eggs each individual fish consumed. We modeled taxon‐specific individual egg consumption as a function of egg availability, individual mass, community composition, number of competitors, and stream velocity using hurdle models in a Bayesian framework. We found that there were diminishing returns for increasing egg abundance increasing egg consumption (i.e., type II functional response) for individual size classes of fish, but that higher egg numbers were needed to benefit diverse consumers. Top models indicated that egg availability and individual fish characteristics (size and taxon) drove egg consumption, while community characteristics (species composition and number of competitors) were not supported. Our results suggest that resource pulses can provide rare opportunities for less dominant sizes and species of fish to consume abundant resources. The current paradigm in the stream fish literature suggests that stream fish communities are structured by dominance hierarchies; however, dominance hierarchies may be less influential where pulsed resources comprise a large portion of the resource base.

中文翻译：

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资源脉冲增加了多物种溪流鱼类组合中成功竞争者的多样性

粮食资源经常在空间和时间上零散分布，过多时被归类为资源脉冲。资源脉冲可以有益于各种消费者的增长，繁殖和丰富。然而，相对未知的是，如何在竞争的消费者之间分配这些资源，以及如何受到脉冲幅度的影响。在这里，我们研究了脉冲资源的大小如何在较小的时空尺度上的自然环境中影响不同规模和不同种类的消费者之间的资源分配。我们专注于鲑鱼卵补贴，以吸引鱼类消费者。我们通过实验在五米长的实验溪流段中添加了不同数量的粉红鲑鱼卵。鸡蛋添加量从6个到3575个鸡蛋跨越了三个数量级。在每个实验区域捕获溪流鱼类（卵的食用者）并用胃灌洗以确定每条鱼消耗了多少卵。我们使用贝叶斯框架中的障碍模型，将特定分类单元的个体鸡蛋消费量建模为鸡蛋可获得性，个体质量，社区组成，竞争者数量和水流速度的函数。我们发现，增加蛋的丰度会增加个体蛋类鱼类的鸡蛋消耗量（即II型功能性反应），而收益却递减，但是需要更多的鸡蛋数量才能使不同的消费者受益。顶级模型表明，鸡蛋的可获得性和个体鱼类的特征（大小和分类群）推动了鸡蛋的消费，而社区特征（物种组成和竞争者数量）却不受支持。我们的结果表明，资源脉冲可以为占主导地位的大小和鱼类物种消耗大量资源提供难得的机会。溪流鱼类文献中的当前范例表明，溪流鱼类群落由优势等级构成。但是，在脉冲资源占资源库很大一部分的情况下，优势层次结构的影响可能较小。